The Tokyo Foundation is an NGO that focusses on a wide array of issues – ranging to policy, economics. The also have a portion of their website dedicated to "Rediscovering the Treasues of Japanese Food." You can discover articles on agar, Japanese shorthorn cattle, or even the Japanese honeybee. These articles offer an interesting academic perspective on the history, economics, culture and development of each of these food sources. While you are there, check out other articles about political assessments of China, Russia, The United States, and beyond. Likewise, discover their intriguing articles on craft, community, and the cost of capitalism. Unique and provactive, The Tokyo Foundation is a wonderful alternative news source and database.
The yuko is an astringent type of citrus fruit recently confirmed to be native to Japan. Aromatic and high in citric acid, the yuko has been used to flavor food. At one time this fruit was in danger of dying out completely, but a successful movement to revive the species has provided a blueprint for other such efforts.
History of the Fruit
It was only recently that the yuko was rediscovered and recognized as an astringent citrus fruit native to Japan. In appearance the fruit resembles the yuzu (Citrus junos) and kabosu (C. sphaerocarpa). When it ripens, the outer rind and flesh turn a bright yellow that calls to mind the lemon. The yuko has many seeds, a sharp but well-rounded flavor, and juicy flesh; the white inner rind is also edible, like that of the hyuganatsu (C. tamurana), another Japanese member of the citrus genus. The rind of the ripened fruit has a sweet scent similar to other fruits like the pomelo and yuzu.
The history of this fruit is far from clear. One theory holds that the yuko came about from natural crossbreeding between other species like yuzu and pomelo. The yuko grows naturally from seed, is polyembryonic, or capable of producing multiple seedlings from a single seed, and carries out monogonous, or asexual, reproduction. There are a number ofyuko trees standing today that have stood for more than a century, and it is believed that this species was in distinct existence by the middle of the nineteenth century.
Today yuko trees grow in areas of the city of Nagasaki like the Doinokubi and Sotome districts. These were part of the same Saga domain during the Edo period (1603-1868), but some 20 kilometers separate them, and it is thought that the yuko developed independently in both of the districts.
Yuko trees grow alongside pomelo and summer orange trees in residential yards and farm fields of the Doinokubi district, where, as in Sotome, people have harvested and consumed their fruit. The trees can also be found alongside area roads, though, suggesting that birds may have scattered the seeds to sprout in various locations. Nagasaki has traditionally been home to a large Christian population, including the clandestine Christians of the Edo period, when the religion was banned, and the area has deep ties to the faith. Some believe that the French missionary Marc Marie de Rotz (1840-1914) sought to spread cultivation of the yuko as a means of improving the living standards of the area's impoverished villagers.
In both Doinokubi and Sotome, yuko is used to add flavor to vinegared side dishes and to garnish fish including sardines. Children eat the fruit and drink its juice. The fruit has traditionally been floated in bathtubs for a fragrant bathing experience and used medicinally to treat the common cold and other ailments. Since the strains in use have come from naturally growing trees, rather than managed, cultivated ones, the fruit shows great diversity in the thickness of its rind, its size, and its flavor. For the people in these communities, leading subsistence lifestyles and depending on both farming and fishing for their livelihoods, this lack of uniformity may have even made the fruit more attractive to them, as they could choose from among the various yuko types according to their intended use.
Beginning in the 1960s, the yuko began disappearing rapidly from the Nagasaki region. There were various reasons for this. First of all, farmers introducing satsuma oranges feared crosspollination would reduce the value of their new crops. Second, mass production of vinegar and other seasonings reduced the need for homegrown citrus fruit. Third, the trees got in the way of farmers' efforts to expand fields for vegetable production. And fourth, the yuko trees grew tall relatively quickly, making it difficult to harvest their fruit. In Doinokubi in particular, urbanization and the expansion of residential neighborhoods accelerated the decline of the species.
In a few short decades the yuko had declined almost to the point of extinction. In 2001 Masanori Kawakami, then the chief of Nagasaki City Hall's branch office in Doinokubi and the head of the local public community center, learned of this threatened fruit and carried out a survey of the remaining trees together with researchers from the Nagasaki Fruit Tree Experiment Station and other organizations. This was the beginning of a movement to protect and revitalize the yuko populations, mainly of the Doinokubi and Sotome districts.
Read the article in its entirity here: http://www.tokyofoundation.org/en/topics/japanese-traditional-foods/vol.-11-the-yuko-a-native-japanese-citrus